Cells secrete hormones and neurotransmitter via exocytosis. Understanding how exocytosis is regulated and how pharmaceuticals and toxins inhibit exocytosis is of broad medical significance. The overall goal of this SBIR project is to use microfabrication technology to develop a robust and easy-to-use prototype device that can assay release of transmitter from individual cells 10- 100 fold faster and cheaper than current approaches and thereby greatly accelerate the pace of biomedical research. In addition, the devices will provide entirely novel capabilities such as the ability to simultaneously image a fluorescently labeled vesicle while measuring release from the same vesicle with an underlying transparent electrochemical electrode. The Specific Aim is to develop and test a prototype transparent multi-well electrochemical-electrode array device. Each of the wells will be a separate experimental chamber and will contain an array of electrochemical electrodes on the bottom. Individual cells will be docked to each electrode through the use of cell-sized microwells and patterning of cell-adhesion molecules. The electrodes will be transparent and patterned on a thin glass substrate to allow simultaneous high-resolution optical and electrochemical measurements. The electrode arrays will be multiplexed using a proprietary approach to simplify the number of connections required to an external amplifier. The specific milestone for Phase 1 is to record quantal exocytosis from at least 100 cells within one hour using a single multi-well device. Achieving this milestone will demonstrate that the prototype device can acquire data ~10-fold faster than the current method using carbon-fiber microelectrodes, and thus will establish that radical improvements in throughput can be achieved in a practical platform. Potential markets for the devices include the biomedical research community, the pharmaceutical industry to carry out high-throughput screening of drugs that target exocytosis, a clinical market to perform automated assays of botulism without the use of laboratory animals and a defense / homeland security market to detect neurotoxin bioweapons with cell-based biosensors. Exocytronics LLC will consult potential academic users / customers to provide feedback on device design, will obtain marketing advice from an experienced corporate partner and will obtain entrepreneurial support while housed in the MU Life Sciences Business Incubator.